NEC ARTICLE310-15 (b)(6)

[norcaldunk]

THIS SECITON OF THE CODE REFERS SPECIFICALLY TO 120/240 VOLT 3 WIRE SINGLE PHASE SERVICES AND FEEDERS.
I AM SERVING INDIVIDUAL APARTMENTS (SINGLE PHASE TO EACH APARTMENT) FROM A 120/208 VOLT THREE PHASE, FOUR WIRE DISTRIBUTION SERVICE AT THE BUILDING.
MY QUESTION IS, DO THE FEEDERS LISTED IN TABLE 310-15(b)(6) APPLY TO THE SINGLE PHASE FEEDERS FROM THE BUILDING DISTRIBUTION CENTER TO THE INDIVIDUAL APARTMENT PANEL, OR IS THIS TABLE ONLY FOR 120/240 SINGLE PHASE SYSTEMS AND FEEDERS?

 

[tom ogryski]

Re: NEC ARTICLE310-15 (b)(6)

You're absolutely right, the section refers to 120/240 volt feeders. Since your feeders are 120/208, I don't believe that you would be allowed to use the ampacities in this table.

 

[tom baker]

Re: NEC ARTICLE310-15 (b)(6)

The table applies to the "main power feeder" for a dwelling unit.
Does your apartment meet the article 100 defintion of dwelling unit?
Is the feeder the main power feeder to each unit?
Is the system a 120/240 3 wire single phase?
If so, then the table would apply.
Also note there is an errata for the table, before you get any further go the the NFPA website and get the errata. The errata lists the allowed wiring methods.

[ December 04, 2003, 03:25 PM: Message edited by: tom baker ]